BIO 1201 1st Edition Lecture 17Outline of Last Lecture I.GenesII.AllelesIII.Monohybrid CrossesIV. Outline of Current Lecture V.Exceptions to Mendelian PatternsVI.Central Dogma of Molecular BiologyCurrent LectureI. Not all genes follow Mendelian patterns (one clear dominant and recessive, controlled by two genes); exceptions include:a. Incomplete Dominance: heterozygote has an intermediate trait between dominant and recessivei. Example: curly hair in peopleb. Codominancei. Example: ABO bloodtyping in humans1. 3 alleles, two of which are dominantc. Environment can alter phenotypei. Example: Siamese cats—pigment only shows at extremities because the gene activates at lower temperaturesd. Polygenic Traits: controlled by more than one genei. Example: skin color and height in humansii. Can usually tell if trait is polygenic if there is a great deal of variation in that trait in a populatione. Gene Linkage: genes will be inherited differently if they are on the same chromosome as opposed to being on different chromosomesi. Especially true if gene is on X chromosome—X-linkedii. X-linked recessive disorders affect more males than femalesII. Central Dogma of Molecular Biology: how genes become phenotypesa. Genes are recipes to make proteins and define protein shape (and therefore the protein’s function)b. Two Step processi. Transcription1. Takes place in nucleusThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.2. RNA polymerase (Pol) makes an RNA molecule complementary in sequence to the gene3. Genes are separated by sequences of DNA that don’t code for anything4. Genes may be active in some cells but not others5. Promoter: at front of every genea. RNA pol is directed to promoter and reads gene sequence as it unwinds the double helix and makes an RNA compliment of the gene (called
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